This invention relates to a ball bearing comprised of a cage having a plurality of ball guides in the form of axially extending guide channels for the load-carrying and non-load-carrying balls and semicircular reversing or turn-around channels connecting pairs of these guide channels together. In such bearings, endless rows of balls are provided in the guide channels, and an outer sleeve closely surrounds the cage and has ball races axially disposed in the bore. The axially extending races for the non-load-carrying balls lie on a greater diameter in the bearing than the axially extending races for the load-carrying balls, and the axially extending races both for the load-carrying and for the non-load-carrying balls are closed off radially outwardly.
In a known ball bearing of this kind, the outer sleeve is made of relatively thick material, and axially extending recesses are formed in its inner bore to receive the non-load-carrying balls, the radially inwardly projecting sections between the recesses serving as races for the load-carrying balls. In the areas of the semicircular channels provided for the recirculation of continuous rows of balls, the inner bore of the outer sleeve is provided with truncoconical flares (i.e. in the shape of portions of the surfaces of truncated cones) leading to annular grooves. The bottom of this annular groove lies at the same diameter of the bearing as the return channels for the non-load-carrying balls. This known ball bearing requires a great amount of material and is quite expensive to manufacture. Furthermore, the radial dimensions of the outer sleeve are relatively great, so that the radial profile of the entire ball bearing is very high. The greater bearing weight necessitated by this arrangement is also disadvantageous in many applications.
A ball bearing is also known in which the outer sleeve is formed of a relatively thin tube having a plain inner surface surrounding the cage and having slots of lesser width than the diameter of the balls in the area in which the balls are not loaded. Depending on the thickness of this tube, the slots may be C-shaped, or solely of an axially extending configuration. The disadvantage of the C-shaped configuration of the slot is that, when the outer sleeve is hardened, the tongues of material enclosed by the C-shaped slots are subjected to a distortion, and the result is that, when the ball bearing is assembled, the balls are unable to roll perfectly in their guides and are pinched to a certain extent. Common to both of these last-named designs is the disadvantage that the strength of the outer sleeve is adversely affected in the area of its midsection by the slots, i.e., in the area in which the load-carrying zones are situated. The same applies also to the cage, whose islands, i.e., the portions between the guide channels of each continuous train of balls, are adequately joined to the rest of the cage ring only on one side, i.e., only in the area of the return channels, due to the only shallowly ascending turn guides and the thin cross sections in which this results. In the area of the races for the load-carrying balls, the cage has a slot open radially inward to allow the balls to contact the shaft. Due to these unfavorable circumstances, the manufacture of the cage from plastic, the material used primarily in the manufacture of the cage, presents great difficulty, especially in the small sizes, both in the production of the cages themselves and in the making of the dies for these cages. In the practical manufacture of these known ball bearings, the cage in the bore also has C-shaped slots formed therein, i.e., the turn channels are also open radially inwardly. In this case the balls also contact the shaft in the turn areas. This results in increased friction and wear.